1. Field of the Invention
The present invention concerns a device for protecting an injection device, in particular an injection device for medical use such as a syringe.
2. Description of Related Art
In this application, the distal end of a part or of the device is considered to be the end farthest away from the injection site. Likewise, in this application, the term “distal direction” refers to the direction of injection, and “proximal direction” designates the direction opposite the direction of injection.
It is known to provide a device for protecting an injection device comprising a body in which the injection device is placed, a sleeve mobile in relation to this body, means enabling the mobility of this sleeve and means enabling the sleeve to be locked in the protective position. The sleeve can be moved between a non-protective position, in which an injection member comprised by the injection device is exposed so as to allow injection, and a protective position, in which the sleeve completely covers the injection member so as to eliminate the risk of contamination of the user by this injection member and to prevent reuse of the injection device. Said injection member is the needle of this syringe when the injection device is a syringe.
Document WO 2005/030301, in the applicant's name, illustrates one such protection device. In this known device, as illustrated by the appended FIG. 1, the means allowing locking of the sleeve 3A in the protective position comprise at least one flexible proximal leg 7A integral with the sleeve 3A, being engaged, in the protective position, behind a corresponding distal edge 51A arranged at the end of a rib 5A integral with said body. The sleeve 3A also comprises, at its proximal part, at least one wall 10A adjacent to the leg 7A, which protrudes in the proximal direction.
The flexible leg 7A has a relatively significant length (it is also part of the means allowing the mobility of the sleeve 3A, being, in the non-protective position, hooked on a proximal rim formed by the rib 5A and, at the end of injection, being bent by a cam surface actuated by the piston rod so as to be freed from this rim). It also has a relatively reduced thickness, such that it can assume a position between the body of the syringe and the body of the device, and is in a material having a degree of elastic flexibility, so that it can be deformed between its hooked position making it possible to maintain the sleeve 3A in the non-protective position and its unhooked position allowing movement of this sleeve 3A toward the protective position.
This flexible leg 7A has the drawback of presenting limited resistance to a force exerted on it longitudinally, having been evaluated at 60 N. This limited resistance does not exclude the possibility of forcing the sleeve 3A toward said non-protective position, the leg 7A then being subject to buckling, i.e. the phenomenon defined by a breaking or bending of the leg subjected to compressive efforts in the direction of its length. This buckling generally leads to irreversible damage to the leg 7A, such that said leg, after a first forcing, no longer adequately maintains the sleeve 3A in the protective position.
Moreover, it has been noted that the resistance value of this leg 7A varies substantially within a same sample of a plurality of devices as the buckling phenomenon is not very repeatable and is poorly controlled. The result is that certain devices from this sample have too limited a resistance to said forcing to effectively provide the desired protection.
The present invention aims to resolve these essential drawbacks, without, however, calling into question the use of the structure of the protection device as previously stated, known by the earlier document mentioned above.